Wear sensing means for rotary compressor



l Aug. 26,1969 J. k. KILBANE 3,463,384

WEAR susme MEANS Fonnoumf coMPnEssoR Filed July 2s.. 1967 United States Patent O M U.S. Cl. 230-138 5 Claims ABSTRACT OF THE DISCLOSURE A sliding vane rotary compressor with openings at the lbottom of the vanes which short circuit adjacent pressure chambers after a predetermined amount of wear has taken place on the vanes, and means for indicating when the short circuit has occurred.

This invention pertains in general to rotary compressors and more particularly to a means to sense the wear on the compressor vanes.

Sliding vane rotary compressors have few moving parts and therefore require little maintenance. However, periodically it is necessary to disassemble the machine to determine whether or not the vanes need to be replaced.

It is a general object and the intention of this invention to provide a fmeans for determining when the vanes of a rotary compressor need to be replaced which does not require a disassembly of the machine.

A further object of the subject invention is to provide a rotary compressor of the sliding vane type with means which provides a short rcircuiting of one compression chamber to the next after a predetermined amount of wear has taken place on the compressor vanes.

A lmore specific object of this invention is to provide a rotary compressor of the hereinbefore described type with means which will cause a change in pressure and temperature of the fluid in the compressor after a predetermined amount of wear has taken place on the rotary vanes and including means which will sense this change.

These and other objects of the subject invention will become more fully apparent as the following description is read in light of the attached drawings wherein:

FIG. 1 is an isometric view partially broken away showing a rotary compressor constructed in accordance with the invention and including temperature sensing means;

FIG. 2 is a side elevation of a modified form of sliding vane; and

FIG. 3 is a view taken along the line II-II in FIG. 2.

Referring to the drawings, a rotary compressor generally designated 6 is shown lconstructed in accordance with the invention. The compressor comprises an outer cylindrical casing 7 having end closures 8. A shaft 9 extends through the compressor end closures and rotatably mounts a rotor 11 within the casing 7. The rotor is provided with a plurality of radially directed circumferentially spaced slots 12. In each of these slots is received a sliding vane 13.

The rotor is mounted eccentrically with relation to the longitudinal center line of the compressor casing so that upon rotation of the rotor the vanes 13 will be forced inward due to contact with the rotor casing and will move outward under the inuence of centrifugal force. The vanes 13, rotor 11 and casing 7 define pressure chambers 15.

As shown in FIG. l, one form of the compressor vanes 13 may have one or more openings 14 extending completely through the lower portion of the vane. As the 3,463,384 Patented Aug. 26, 1969 ICC vanes wear, due to the relative sliding motion between their outer surface and the 'compressor casing, the vane will extend further out of the slot 12. When the highest point on the openings l14 pass above the rotor surface, a direct short circuit between the two adjacent compression chambers 15 exists. Therefore, the higher pressure gas in the smaller chamber will seep Iback into the lower pressure gas and will be worked upon again as the rotor rotates. This will cause an increase in the temperature of the gas. This increase in temperature will `be a substantial rise as compared to the rise in the temperature as the gas is compressed in the ordinary manner.

A temperature sensing means 16 is provided in the compressor casing 7. The sensing means 16 senses the unusual increase in the temperature of the gas and sends a signal to the thermocouple alarm 17. This signal is then transferred to a motor control switch 18 which shuts down the compressor and also sends a signal to an alarm enunciator 19 which may either sound an alarm or turn on a light to indicate to the operator that the compressor vanes need replacing.

FIGS. 2 and 3 show a modified form of compressor vane. In this modified form a groove 21 is provided in the lower portion of the compressor vane. This groove is of sufficient depth so that it will wear through due to the friction between the surface of the vane and the sides of the slots 12. The depth of the groove 21 is such that it will wear through when a predetermined amount of wear has taken place on the vane 13. A direct short circuit will then occur between the two adjacent compression chambers. This again will sound the alarm in the same manner as indicated above.

Although only two embodiments of the subject invention have been herein shown and described, other embodiments will be obvious to those skilled in the art after reading this description and it is intended that all such embodiments as come within a reasonable interpretation of the appended claims be covered.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A system for sensing the wear of the vanes of a rotary compressor of the type comprising a cylindrical compressor casing; a rotor supported for rotation Within said casing; slots in said rotor; a vane slidably contained in each of said slots and having an edge forced into fluid sealing engagement with an interior surface of said casing, said vanes defining with said rotor and said casing separate sealed pressure chambers; passage means through that portion of at least one of said vanes which remains in a slot, said passage means being closed by said slot until a predetermined amount of wear of the Vane has occurred at which time said passage extends above said slot and fluid communication is established between adjacent pressure chambers; and a sensing device connected to said compressor to indicate when said fluid communication has 'been established between pressure chambers.

2. A system for sensing the wear of the vanes of a rotary compressor of the type comprising a cylindrical compressor casing; a rotor supported for rotation within said casing; slots in said rotor; a vane slidably contained in each of said slots and having an edge forced into fluid sealing engagement with an interior surface of said casing, said vanes defining with said rotor and said casing separate sealed pressure chambers; walls defining a groove extending only partially through the face of at least one of said vanes and being void of fluid communication with the opposite face of' said vane, said groove causing fluid communication with adjacent pressure chambers after a predetermined amount of wear of the vane has occurred; and a sensing device connected to said compressor to indicate when said Huid communication has been established between pressure chambers.

3. A system according to `claim 1 wherein said sensing device is temperature responsive.

4. A system according to claim 1 wherein said sensing device is operatively connected to a motor control switch to stop operation of said compressor when said predetermined vane wear has occurred,

5. A system according to claim 1 wherein said sensing device actuates an audible alarm when said predetermined wear has occurred.

References Cited UNITED STATES PATENTS 1,233,855 7/1917 Eidson et al. 230-152 2,716,946 9/ 1955 Hardy.

3,102,493 9/1963 Davin 103-135 3,238,885 3/1966 Paski 10S-136 DONLEY I. STOCKING, Primary Examiner 10 WILBUR I. GOODLIN, Assistant Examiner U.S. Cl. X.R. 230-152 

